Abstract
Voltage clamp studies were performed on the dorsal integument of Hirudo medicinalis. Under apical calcium-free conditions an inward-directed component of transepithelial current was activated by changes of transepithelial voltage. Depolarization caused up to 50% increase of the transepithelial sodium current. Hyperpolarization had no comparable effects. With calcium (1.8 mM) or amiloride (100 μM) in the apical solution and in sodium-free solutions the inward-directed current failed to increase after depolarization. Activation also occurred under chloride-free conditions. Permeabilization of the apical membrane by nystatin (5 μM) increased the current activation significantly. After nystatin, calcium as well as amiloride lost their inhibitory effects. This indicates a basolateral localization of the voltage-dependent conductance. Vesicle insertion or cytoskeletal structures are probably not involved in regulation, as seen by the lack of effects of brefeldin A and the cytochalasins B and D. However, serosal hyposmolar solutions (170 mosmol · l−1) caused a reinforced activation of the current. Our results indicate a voltage-dependent conductance in a tight sodium-absorbing epithelium.
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Accepted: 22 January 1998
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Schnizler, M., Clauss, W. Characterization of a voltage-dependent conductance in the basolateral membrane of leech skin epithelium. J Comp Physiol B 168, 295–302 (1998). https://doi.org/10.1007/s003600050149
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DOI: https://doi.org/10.1007/s003600050149